Your thyroid sits in front of your windpipe, between your adam’s apple and collarbone, and produces hormones that travel throughout your body to ensure the proper functioning of multiple systems. 

The hormones produced by your thyroid are vital to many aspects of your health. They are collectively known as your thyroid hormones, influencing your brain, nervous system, immune system, metabolism, organ functioning, and even gut health.

Here are just a few of the critical body systems affected by thyroid hormones:

  • Bone Metabolism
  • Immune System
  • Brain & Nervous System
  • GI Function & Stomach Acid Production
  • Liver & Gallbladder
  • Growth & Sex Hormones
  • Fat Burning
  • Insulin & Glucose Metabolism
  • Healthy Cholesterol Levels

Primary Hormones

The primary thyroid hormones are T3 (triiodothyronine) and T4 (thyroxine) and are the thyroid hormones most often tested in laboratory panels. T3 supports brain and heart function and plays key roles in digestion and bone health. T4 is responsible for metabolism, mood, and core temperature. Your thyroid produces more T4 than T3 because the T4 hormone is inactive and converts into T3 to become active. 

Every cell in the body has a receptor site for thyroid hormones, so any disruption in thyroid function will cause a disruption in metabolism and almost every organ and tissue in the body. This makes it vitally important that thyroid hormones are at peak performance at all times. 

What affects Thyroid Health

Several factors can disrupt proper thyroid functioning and hormone production. Stress or calorie deficiency are the two most common lifestyle changes that affect thyroid health. When treating patients with suspected thyroid issues, it is vital to address the gut and liver first because of the direct correlation between these organs and the production of thyroid hormones. 

Significant calorie deficiency can cause a severe impact on your hormone production. Your body prioritizes where it can best utilize the limited energy supply in this state, often opting for brain and body functioning and neglecting the production of hormones through the thyroid gland. Additionally, the micronutrients in your gut directly influence hormone production, specifically the ability of T4 to convert into T3. So, when your body is in a calorie deficit, it lacks sufficient nutrients to produce the right amount of hormones at the right time.

Hypothyroidism is a widespread disruption to the normal functioning of the thyroid. The most common cause ofSymptoms of thyroid dysfunction are fatigue, increased sensitivity to cold, constipation, dry skin, weight gain, puffy face, hoarseness, muscle weakness. hypothyroidism in the U.S is Hashimoto’s Thyroiditis. Essentially, the body attacks and destroys the Thyroid gland. This classifies Hashimoto’s as an autoimmune disorder, not a thyroid disorder. 

Trauma, infections, and disease also disrupt hormone production by limiting the hormones produced or sending their production into overdrive. Toxins such as pesticides, mercury, cadmium, lead, or radiation are well documented in their adverse effect on thyroid health as well. 

Testing and Panels

Your adrenal glands produce hormones, just like your thyroid. Getting to the root of an endocrine issue is often difficult because so many glands produce hormones that use the same production pathway, so glandular issues can challenging to get under control. Running a full panel of thyroid tests can be instrumental in determining the root cause of symptoms you may be experiencing. In many instances, the problem isn’t in the thyroid at all. That is why only checking T4 and T3 can be misleading. You may even end up on medication that is inappropriate or harmful to your thyroid. 

Thyroid laboratory panels should include both Total and Free T3 & T4. A Total T3 and T4 test will show the amount of free and bound hormones in the body, while Free T3 and T4 will only show the free hormones. 

In order to get a complete picture of thyroid function, a thyroid panel should include: TSH, Total T4, Total T3, T3 Uptake, Reverse T3, Thyroid AntibodiesPanels should also test the level of Thyroid Stimulating Hormone (TSH)- the hormone responsible for signaling the thyroid to produce hormones- as well as T3 uptake- the ability of T3 to bind with proteins. Reverse T3 (the ability for T4 to convert into T3 and Thyroid Antibodies) testing should be run to ensure antibodies are at appropriate levels and are not over or underperforming. 

General practitioners often only run a handful of these tests instead of the full panel. This can lead to misdiagnosis or no diagnosis at all. Your T3 and THS levels may be well within the defined clinical lab range, while T4 is outside the normal levels. Without the full spectrum of tests, your symptoms may go unresolved or even be written off as psychosomatic.

 Clinical Lab Range vs. Functional Lab Range

Understanding the difference between clinical and functional lab ranges can be the difference between prevention and intervention when it comes to thyroid health. A clinical range thyroid test will probe for an issue that is already present, while a functional range test is used to assess if there is potential for an issue. Most MDs will run a limited (usually T3/ T4/ and TSH) test for thyroid function.

“Lab normal” is based on the statistical average of samples tested rather than what is optimal for the human body.  Thus “normal” ranges can shift over time based on the lab samples and the health of people getting tested regularly.  Studies show 90% of tests come back “lab normal,” meaning they are within the range set by the lab. This can potentially result in your doctor dismissing the need for serious medical action. So even if you feel tired, have headaches, cold hands, and feet, brain fog, feel exceedingly nervous or depressed, your hair is falling out, and you can’t seem to lose weight, the doctor will be inclined to tell you there is nothing seriously wrong with you, and you should just wait and see what happens.

When test results are outside of functional but within clinical ranges, action can be taken to resolve symptoms before they become a serious medical issue. If your lab results show that your thyroid hormones are testing outside the clinical lab range, there is a serious medical condition that requires medical intervention. The much narrower range on a functional lab test will help functional medicine doctors know exactly how to intervene on a sub-clinical level before clinical signs of thyroid dysfunction shows up